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Proposal Number: 10300001

Title: Resolving short supersoft source states of optical novae in the core of M31

PI Name: Wolfgang Pietsch

We propose to continue the monitoring of the M31 core with 5x23ks XMM EPIC and 5x20ks Chandra HRC-I observations equally distributed from Nov 2008 to mid Feb 2009 to determine additional lightcurves for short SSS states of optical novae. SSS states with <100 d duration indicate accreting massive white dwarfs. They are proposed as SN Ia progenitors and determining their frequency is very important. We will correlate detected sources with novae from optical monitoring. With a nova rate in the field of ~25/yr and SSS states lasting from weeks to years we will follow light curves of many novae. Durations of the nova SSS state will allow us to constrain envelope and whitedwarf masses. We will also monitor time variability of ~200 M31 centre X-ray sources (mostly XRBs).

Proposal Number: 10300026

Title: Resolving short supersoft source states of optical novae in the core of M31

PI Name: Peter Predehl

We propose to continue our monitoring of the M31 core by 2x20ks Chandra HRC I observations mid and end Feb 2009 to determine the light curves of the short SSS states of optical novae. SSS states with $<$100 d duration indicate accreting massive white dwarfs (WD). They are proposed as SN Ia progenitors and determining their frequency is very important. The detected sources will be correlated with optical nova positions from monitoring programs covering the same area. With a nova rate in the field of ~25/yr and SSS states lasting from weeks to years we will simultaneously follow light curves of many novae. The durations of the nova SSS state will allow us to constrain the envelope and WD masses. We will also monitor time variability of ~200 M31 centre X-ray sources (mostly XRBs).

Proposal Number: 10300323

Title: Chandra Observation of a New Galactic Globular Cluster -- FSR 584

PI Name: David Pooley

We propose a 20 ksec ACIS-S3 observation of the star cluster FSR 584, which was recently discovered in 2MASS data and argued to be a globular cluster. This heavily obscured object lies nearly in the Galactic plane at only 1.4 kpc, making it the closest globular cluster. A relatively short observation will allow us to take a census of the X-ray emitting objects in this cluster (with Lx > 4x10^30 ergs/sec), such as quiescent low-mass X-ray binaries, cataclysmic variables, millisecond radio pulsars, and chromospherically active main-sequence binaries. As our work with another recently discovered globular cluster in the plane (GLIMPSE-C01) has shown, Chandra data can be used to help rule out the alternative for this object, namely, an old open cluster.

Proposal Number: 10300356

Title: CP Puppis, a template for the secular evolution of novae

PI Name: Marina Orio

We propose a Chandra HETG observation of the extraordinary quiescent nova CP Puppis, to follow up on our XMM-Newton study. The HETG spectrum will provide a tighter constraint on the cooling flow model fit, which we have used to infer the white dwarf mass and the mass accretion rate in this nova, testing the theory of nova outbursts. Chandra will allow us to spatially resolve the nova shell, and to understand whether the O VII triplet originates in the shell or whether photoionization is important. We will perform sensitive diagnostics using a wide range of lines. CP Puppis offers a unique possibility to prove the dependence of the thermonuclear burning evolution on the physical parameters of the system.

Proposal Number: 10300452

Title: RS Ophiuchi: First X-ray Jet from a Nova

PI Name: Jennifer Sokoloski

A highly collimated outflow from a nova has been imaged for the first time, both in the radio, and in the X-rays with Chandra. With its high velocity and its synchrotron radio lobes, this outflow from the symbiotic star RS Ophiuchi pushes the exploration of non-relativistic jets into a new regime. The production of a collimated jet within a few days of outburst also challenges the assumption that in a nova the blastwave sweeps away the accretion disk. We propose a second Chandra image of the evolving jet from RS Ophiuchi to determine the properties of this new type of jet, the conditions that led to its production, and the nature of the accretion disk that must have survived the nova explosion. This work has implications for our fundamental understanding of both jets and novae.

Proposal Number: 10300531

Title: Grating spectroscopy of a bright nova in outburst

PI Name: Thomas Nelson

We propose a TOO program to obtain LETG spectroscopy of a classical or recurrent nova in outburst, if it is observed to turn into a luminous supersoft X-ray source with Swift. In the rare case that a nova has unusually luminous hard X-ray flux in the initial stages, we also propose to obtain a HETG spectrum of the ejected shell. Our aims are: a) to constrain the mass, temperature and chemical composition of the white dwarf by analyzing the spectrum, b) to correlate spectral and temporal variablility during the nuclear burning phase, and c) to use the HETG to explore wind mass loss in a recurrent nova. The proposed study is important not only for nova/CV theory, but for understanding supernova Ia progenitors.

Proposal Number: 10300566

Title: The Nature of the Soft Component in the Symbiotic Star CH Cygni

PI Name: Koji Mukai

The symbiotic star CH Cyg consists of an M giant and a white dwarf, and displays a two-component X-ray spectrum. The absorbed hard X-ray component is likely due to accretion onto the white dwarf. The unabsorbed soft X-ray component is thought to be either due to colliding winds or due to photoionization of the M giant wind by the hard component. We propose to obtain a high signal-to-noise grating spectrum of CH Cyg to resolve the origin of its soft component. Once we know its origin, we can begin to probe the environment around the white dwarf using the detailed spectral shape of the soft component. We propose this as a slow TOO, to be triggered when we know that CH Cyg is X-ray bright.

Proposal Number: 10300586

Title: PlaN-B: The hyperactive coronae of interacting companions in planetary nebulae

PI Name: Orsola De Marco

With this proposal we seek to obtain ACIS-S spectra of two central stars of planetary nebula, known to have post-common envelope central stars with main sequence companions. We expect these companions to have been spun up during the common envelope and to have X-ray bright cornoae as a result. These detections will establish the X-rays as a way of detecting M-type main sequence companions to central stars, which are hard to detect with other methods. The Lx and Tx will be compared to prediction from models and will be used to carry out a first determination of the amount of mass and angular momentum accreted during the common envelope.

Proposal Number: 10300600

Title: Uncovering the interacting binary population in NGC 6681

PI Name: Andrea Dieball

We propose to carry out 70 ksec X-ray imaging of the globular cluster NGC 6681 with Chandra. This cluster was extensively observed in the FUV with HST, yielding the deepest FUV survey of a globular cluster to date. Our X-ray observations will allow us to (i) find X-ray counterparts to the white dwarf - main sequence star binaries in our ultra-deep FUV survey, thus identifying and confirming the cataclysmic variables amongst them; (ii) detect the X-ray faintest interacting binaries (IBs) in this cluster; (iii) classify all X-ray sources based on their X-ray, FUV and optical properties; (iv) and finally, using all the information obtained, test models for IB formation and evolution and verify the empirical results emerging from previous work on other clusters.

Proposal Number: 10300704

Title: Understanding the Current Dynamical States of Globular Clusters

PI Name: David Pooley

We appear to be on the verge of a major paradigm shift in our understanding of the current dynamical states of Galactic globular clusters. Fregeau (2008) brought together two recent theoretical breakthroughs as well as an observational breakthrough made possible by Chandra -- that a globular cluster's X-ray source population scales with its dynamical encounter frequency -- to persuasively argue that we have misunderstood the dynamical states of Galactic globular clusters. The observational evidence hinges on Chandra results from clusters which are classified as "core collapsed," of which there are only a handful of observations. I propose a nearly complete census with Chandra of the rest of the "core collapsed" globular clusters.

Proposal Number: 10300769

Title: Searching for Millisecond Pulsars in Extremely Low-Mass White Dwarf Binaries

PI Name: Craig Heinke

Several extremely low-mass white dwarfs, with masses below 0.24 solar masses, have recently been discovered in large surveys. These white dwarfs cannot be formed through the evolution of single stars, and several are known as companions of millisecond radio pulsars. We propose a search for X-ray emission from six relatively bright extremely low-mass white dwarfs to distinguish between neutron star vs. white dwarf companions. New millisecond pulsars with companions amenable to spectroscopy are of great interest, while ruling out neutron star companions will put constraints on common envelope models for double white dwarf evolution.

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